Draw a line with PIXI and move it with TweenMax

Question

I watched an example of using this both framework (PIXIjs and GSAP). So I wanted to use it

I'm a little bit stuck on a case. So what I want to do is to draw 3 line that match the border of my window. That's fine, but In a second step, I'd like that this lines move without leaving the border.

Here is my little code for this part

// This is how I create the line
    var lineArray = [];

    for (var i = 0; i < 3; i++) {

        var line = new PIXI.Graphics();
        line.lineStyle(1, 0xf3a33f);

        if(i == 0) {
            line.moveTo(getRandomInt(0, window.innerWidth), window.innerHeight);
            line.lineTo(getRandomInt(0, window.innerWidth), 0);
        } else if(i == 1) {
            line.moveTo(0, getRandomInt(0, window.innerHeight));
            line.lineTo(window.innerWidth, getRandomInt(0, window.innerHeight));
        } else {
            line.moveTo(getRandomInt(0, window.innerWidth), window.innerHeight);
            line.lineTo(window.innerWidth, getRandomInt(0, window.innerHeight));
        }

        line.endFill();
        line.alpha = 0;

        stage.addChild(line);
        lineArray.push(line);

    }

// And this is how I want to animate it

var timeline = new TimelineMax({ paused: true });
for (var i = lineArray.length - 1; i >= 0; i--) {
    lineArray[i].beginFill(0xf3a33f, 1);
    timeline.add(TweenMax.to( lineArray[i], .05, {alpha: 1}), 1.25);
}
timeline.play();

Is there a way to move the lineTo(x, y) and moveTo(x, y) of the graphics shape ? I thought that I can redraw each time that I move the line, and destroy the old one, but I hope that there is a easier way to do that.

Cheers, H4mm3R

Answer 1

If you wish to be able to animate / tween the moveTo and lineTo values then the graphics object of each line will need updating i.e. clear(); and then redraw with the usual moveTo and lineTo calls with new values. All happening inside a render function which updates your canvas timely.

The other thing is you will need a way to keep a track of your start and end values. I have resorted to arrays by the names currPoints and destPoints in my example below, code of which is as follows:

JavaScript:

var lineWidth = 2,
    lineColor = 0xf3a33f,
    length = 4,
    currPoints = [],
    destPoints = [],
    lineArray = [],
    duration = 1.4,
    ease = Power4.easeInOut,
    staggerFactor = .06;

function init() {
    initScene();
    initLines();
    animateLines();
    TweenLite.ticker.addEventListener('tick', render);
}

function animateLines() {
    for (var i = 0; i < length; i += 1) {
        TweenMax.fromTo(lineArray[i], duration, {
            alpha: 0
        }, {
            delay: i * staggerFactor,
            alpha: 1,
            repeat: -1,
            yoyo: true,
            repeatDelay: duration * .5,
            ease: ease
        });
        TweenMax.to(currPoints[i].moveTo, duration, {
            delay: i * staggerFactor,
            x: destPoints[i].moveTo.x,
            y: destPoints[i].moveTo.y,
            repeat: -1,
            yoyo: true,
            repeatDelay: duration * .5,
            ease: ease
        });
        TweenMax.to(currPoints[i].lineTo, duration, {
            delay: i * staggerFactor,
            x: destPoints[i].lineTo.x,
            y: destPoints[i].lineTo.y,
            repeat: -1,
            yoyo: true,
            repeatDelay: duration * .5,
            ease: ease
        });
    }
}

function initLines() {
    var line;
    for (var i = 0; i < length; i += 1) {
        line = new PIXI.Graphics().lineStyle(1, 0xf3a33f);
        if (i == 0) {
            currPoints[i] = getPoint(getRandomInt(0, window.innerWidth), window.innerHeight, getRandomInt(0, window.innerWidth), 0);
            destPoints[i] = getPoint(getRandomInt(0, window.innerWidth), window.innerHeight, getRandomInt(0, window.innerWidth), 0);
        } else if (i == 1) {
            currPoints[i] = getPoint(0, getRandomInt(0, window.innerHeight), window.innerWidth, getRandomInt(0, window.innerHeight));
            destPoints[i] = getPoint(0, getRandomInt(0, window.innerHeight), window.innerWidth, getRandomInt(0, window.innerHeight));
        } else {
            currPoints[i] = getPoint(getRandomInt(0, window.innerWidth), window.innerHeight, window.innerWidth, getRandomInt(0, window.innerHeight));
            destPoints[i] = getPoint(getRandomInt(0, window.innerWidth), window.innerHeight, window.innerWidth, getRandomInt(0, window.innerHeight));
        }
        line.moveTo(currPoints[i].moveTo.x, currPoints[i].moveTo.y);
        line.lineTo(currPoints[i].lineTo.x, currPoints[i].lineTo.y);
        main.addChild(line);
        lineArray.push(line);
    }
}

function initScene() {
    renderer = PIXI.autoDetectRenderer(window.innerWidth, window.innerHeight, {
        view: document.querySelector('canvas'),
        antialias: true
    });
    main = new PIXI.Container();
}

function render() {
    renderer.render(main);
    for (var i = 0; i < length; i += 1) {
        lineArray[i].clear();
        lineArray[i].lineStyle(lineWidth, lineColor);
        lineArray[i].moveTo(currPoints[i].moveTo.x, currPoints[i].moveTo.y);
        lineArray[i].lineTo(currPoints[i].lineTo.x, currPoints[i].lineTo.y);
    }
}

function getPoint(xMoveTo, yMoveTo, xLineTo, yLineTo) {
    return {
        moveTo: {
            x: xMoveTo,
            y: yMoveTo
        },
        lineTo: {
            x: xLineTo,
            y: yLineTo
        }
    };
}

function getRandomInt(min, max) {
    return Math.floor(Math.random() * (1 + max - min) + min);
};

//
init();

Play with the jsFiddle and let me know if this is what you were looking for.

T